Conventional systems for dilating blood vessels and/or structures (e.g., stents or stent grafts) positioned in a blood vessel utilize balloon-like structures (“balloon dilators”). Such structures are typically made from essentially impermeable materials. When such a device is expanded to perform a dilation, blood flow is entirely or substantially occluded through the blood vessel in which the balloon dilator is being used. Such an occlusion of blood flow could, if continued for too long, harm the patient, since portions of the body downstream of the balloon dilator will not receive blood while the flow is occluded or substantially hindered. Thus, the length of time balloon dilators may be dilated is limited and this can hinder proper completion of the dilation procedure.
A similar problem with balloon dilators arises when a dilation procedure is being performed in a portion of the circulatory system where there is a branch in the blood vessels, such as where the iliac or renal arteries are side vessels that branch from the aorta. In that case a balloon dilator may cover a side vessel and partially or totally occlude blood flow to the side vessel.
Another problem with balloon-like dilators is called the “jackhammer effect.” Because blood flow is substantially or entirely occluded when balloon dilators are dilated, the blood pressure upstream of the balloon dilator can be significant and may cause the balloon dilator, and any structure (such as a stent or stent graft) positioned in the blood vessel and that is being dilated by the balloon dilator, to move out of the desired position, effectively pushed down stream (i.e., in the antegrade direction) by the upstream blood pressure. Because of this problem accurate placement of such structures can be difficult utilizing balloon dilators.